Hydraulic classifier



Aug 9, 1955 w. T. MARsToN HYDRAULIC C]` .SSIF'II'R 4 Sheets-Sheet l Filed Deo. 9, 1955 IMI' INI 'ENTORS William T. Marston J{TTORNEY Aug. 9, 1955 w. T. MARSTON HYDRAULIC CLASSIFIER 4 Sheets-Sheet 2 Filed DGO. 9, 1953 WW/myy/WWWWWWWHL I NVE NTORS william T. Marston TTORNE Y Aug. 9, 1955 w. T. MARsToN HYDRAULIC CLASSIFIER 4 Sheets-Sheet 3 Filed DeG. 9. 1953 IIIIIIIIIIIIIIJ jO o @#1 www lfm@

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I NVE NTORS William T. Marston /I TTOR NE Y Aug. 9, 1955 w. T. MARsToN HYDRAULIC CLASSIFIER 4 Sheets-Sheet 4 Filed Dec. 9. 1955 uw n b\ kh( f km m\ /w /m i .vm .fwn /m s. 9v mv n mm k IIIIIIIIIIIIIIIIIIIIIIIII Il mm, m .i

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l N I/'ENTORS William T. Marston TTOR NE Y United States Patent O HYDRAULIC CLASSIFIER William T; Marston, Denver,

Colo., assgnor to The Dorr Company, Stamford, Conn.,

a corporation of Delaware Application December 9, 195s, serial No. 397,209 5 Claims. `(Cl. 209-18) fraction of sizes, these fractions herein to be simply termed the coarse fraction and the fines fraction, or else the oversize and the undersize. The coarse` fraction then contains substantially all sizes above an intermediate size while the fines fraction contains substantially all those that are smaller than the intermediate size.

Hydraulic separation such as herein contemplated takes place in a classification pool into which the pulp is fed, while the coarse fraction is withdrawn from the bottom of the pool andthe fines fraction overflows from the pool across a weir. ln order to aid and control the separation, the mixture of particle sizes while in transit through this pool may be kept mobilized by`being sub-` jected to the effect of controlled mechanical agitation,

or subjected to the effect of a stream of auxiliary socalled hydraulic operating water up-flowing through the pool at a controlledvelocity; however, as contemplated by this invention, the mixture in the pool is subjected to the joint effects of both mechanical and hydraulic action, with the result that a desired coarse fraction above a certain mesh size will collect at the bottom of the pool to be withdrawn therefrom, while a corresponding fraction of fine sizes with its carrier water overflows from the pool, this to afford superior means of separation control presently to be set forth. j

It is among the basic problems in such wet `classification or separation treatment that there be effected as sharp a separation as possible between the oversize and the undersize or else between the underflow sizes and the overflow sizes; thus the aim is to conduct the classification treatment in such a manner or with such type of apparatus that each of the two fractions be obtained as free as possible from stray sizes of the`other fraction.

Another basic problem in such wet classification treatment or apparatus is that of providing control means whereby the point of separation or fractionation or cut between the two groups of sizes, the oversize and the undersize can be readily established and accurately adjusted. For example, if the feed be of a run containing particle sizes ranging, say, from 28 to 200 mesh, thenit should be possible, for example, to make a clean split at say, 100 mesh, yet it should be possible to readily shift the cut to, say, 48 mesh. This calls for providing simple and effective means for so adjusting or shifting the cut while deriving the respective size fractions clean, that is with a minimum of stray sizes admixed thereto. For example, the importance of producing a clean coarse fraction is apparent where the classification apparatus operates in closed circuit with a wet grinding mill, the mill to receive coarse fraction particles for regrinding, and where the admixture of an appreciable amount of undersize or stray sizes would burden the circulating load through the mill and would Patented Aug. 9, 1955 accordingly reduce its efficiency as well as that of the circuit as a whole.

Moreover, there is the general problem that such an apparatus should be capable of handling effectively a feed slurry containing a relatively wide range of particles of extreme sizes, that is, from relatively very fine to relatively very coarse.

Also, there is to be considered in the operation of such classification treatment and apparatus the degree of dilution of the feed pulp, since it is desirable to produce a separation which remains substantially stable in spite of possible variations in the degree of feed dilution; another aspect lies in the fact that it may be desirable to derive the overflow of fines at the highest possible density, there being the difficulty that a high rate of hydraulic water required might run counter to the goal of attaining the desired degree of overflow density.

The invention provides improvements over the wet classification machine employing the joint or compound effect of mechanical and hydraulic classifying action shown in the patent to W. C. Weber, No. 2,302,588, whichproduces a sharp cut easily and accurately controllable, and which is operable with a minimum of hydraulic operating water, capable of absorbing appreciable changes in the dilution of the feed pulp substantially without affecting the cut itself, even though capable of producing the overflowing undersize fraction at relatively great density, and of handling a feed pulp containing a wide range of particle sizes from fine to coarse.

It is among the objects of the present invention to produce a` machine possessing at least the operational characteristics and capabilities of the machine in the aforementioned patent, yet to be simpler of construction, lighter in weight, cheaper to build, as well as simpler to maintain, simpler to overhaul and simpler to service, and last but not least, which is more compact and which lends itself to a variety of structural modifications whereby it is conveniently and compactly adaptable for struc-` tural integration in a treatment system such as closedcircuit grinding. The significance of these objects will appear more precisely from the following outline of the machine shown in that patent. ln that machine, the pulp is fed to a signicantly shallow pool the bottom of which is formed by a horizontal circular false bottom in the form of a perforated plate usually termed a constriction plate. A hydraulic supply chamber is associated with the underside of the constriction plate unitary therewith and has hydraulic operating water fed thereto continuously in order that such auxiliary water may con-` tinuously rise in the pool through and upwardly from the constriction plate at a controllable rate, thus helping to maintain the particles in the pool in a mobilized state. Moreover, this hydraulic chamber with its constriction plate is mounted for oscillatory movement about a vertical axis by means of a hollow vertical column rising from the center of the constriction plate and suspended from an overhead bearing structure which carries drive mechanism for imparting the oscillatory movement through the column to the constriction plate and its associated hydraulic supply chamber. The slurry or pulp is fed to a central annular feed well surrounding the column, `and under normal operating conditions the pulp in the pool is subjected to the joint effect of the oscillatory motion of the constriction plate and of the hydraulic water rising therethrough. A uniform distribution of hydraulic water over the entire bottom of the pool is thus obtained not only by reason of the fact that the water is being introduced by the great many holes in the constriction plate, but also because these holes are constantly being oscillated incident to the oscillatory motion of the constriction plate.

The classifier pool is furthermore defined] by a cylindrical stationary boundary wall the top edge of which constitutes an overflow Weir for discharging the undersize fraction of the pulp. This cylindrical boundary wall of the pool is concentric with the constriction plate although of a somewhat smaller diameter so that it is spaced slightly inwardly from the periphery of the constriction plate, yet also spaced upwardly from the marginal portion of the constriction plate. Thus, the constriction plate may oscillate beneath the stationary boundary wall, with the vertical distance between this wall and the constriction plate constituting an annular sands passage or solids transfer passageway leading outwardly from the pool bottom to allow for the outward migration and removal of the oversize fraction of the pulp from the pool. Importantly, along the periphery itself of the constriction plate there is provided what is herein termed a submerged sands discharge Weir over which spill the sands or coarse fraction particles down into a receiving chamber which in turn surrounds the constriction plate. The sands discharge Weir rises to a level at least somewhat higher than the sands passage, so that thereby there is maintained an annular sealing column of sands in transit between the passageway and the Weir.

The annular space between the constriction plate and the surrounding receiving chamber is covered and closed by a top portion of the receiving chamber, which top portion in fact supports the cylindrical boundary wall of the pool by being rigidly connected therewith.

A body or column of clear water maintained in the sands receiving chamber defined by a clear water overflow Weir of adjustable height balances the column of pulp or mobilized particles in the pool, and this balance represents a hydraulic equilibrium condition in the machine, whereby the separation or cut is readily controllable, namely, as by adjustment of the height of the clear water overflow Weir.

The coarse fraction particles upon the oscillatory constriction plate will move or migrate outwardly, radially in all directions towards and through the sands discharge passage and over the submerged sands discharge Weir which surrounds the passage, and into the surrounding sands receiving chamber whence they can be removed into emergence from a body of clear water as by any suitable conventional elevating means or by controlled spigot discharge means.

Thus, it is among the more specific objects of this invention to provide a machine which, while possessing at least the operating features and advantages of a machine such as above outlined, is simpler, lighter and cheaper of construction, with a substantial reduction of the oscillatory, or moving, masses, which is more compact and which is more readily and more compactly adaptable to environmental structural conditions, for example, in what are known in metallurgical operations as closed circuit grinding systems.

The objects of this invention are attained by a machine which is functionally similar to the one disclosed in the copending application of Harold B. Coulter, Serial No. 397,205 filed December 9, 1953, concurrently herewith in that it provides a classifying pool where the feed pulp enters at a point spaced from the point of fines overflow discharge and from the point of sands underow discharge. For example, the pulp may pass in a longitudinal direction from end to end through the pool undergoing classiiication, the underflow discharge being by way of a sands passage at the bottom of the pool and through a connecting sands column outside the passage. The desired kind of classification of the pulp in the pool is effected by the conjoint action of hydraulic water being introduced in substantially uniform distribution at the bottom of the pool and of horizontal longitudinal back-and-forth or vibratory movement of the bottom face of the pool. This movement is such as to provide sufficient acceleration and deceleration within its vibratory cycle, to continuously induce and maintain an intensified degree of relative movement between the surface and the strata of oversize particles sup- 3. ported thereby. The cut between the two fractions is controllable by Way of adjusting a static hydraulic counterpressure effective at the sands discharge passage. One mode of so controlling the hydraulic counter-pressure is by way of a water column superimposed upon the sands column and defined by an adjustable clear water overflow at the superelevation level. That is to say, the oversize particles from the sands column may be allowed to spill into a clear water chamber thence to be removed upwardly by suitable elevating mechanism, or to be removed downwardly by a suitably controlled spigot discharge valve. The fines fraction discharges by overflowing from the classifier p'ool.

In distinction from the apparatus of the above mentioned copending application, this invention provides a machine which is organized in such a manner that the clasier pool is heldin and by a stationary solid tank structure which is provided with an auxiliary vibratable bottom element mounted within the tank structure so as to perform horizontal guided vibratory movement therein. This invention further .provides hydraulic sealing means whereby to prevent solids from the classifier bath from entering and obstructing the space below the vibratory bottom, that is the space between the vibratory bottom and the surrounding solid bottom portion of the tank structure, which hydraulic sealing means will discourage solids from reaching the marginal guide faces between the vibratory bottom and the surrounding stationary tank structure. According to this invention such hydraulic sealing means are provided by pressure water supplied to the chamber underneath the vibratory bottom, which chamber is thus formed by the vibratory bottom together with the surrounding bottom portion of the solid tank structure.

That is to say, the vibratory bottom is peripherally or marginally guided by engaging in grooved horizontal guide portions provided by the stationary tank structure so as to perform therein the required horizontal reciprocatory movement relative to the stationary structure; during operation, pressurewater from the chamber below the vibratory bottom continuously passes through operating clearances between the moving and the stationary parts along and around the peripheral edge portions of the vibratory plate, the sealing water thus escaping upwardly through these clearances to and into the classifier pool itself in sufficient quantity to discourage solids from entering the groove portions proper.

According to one embodiment the upward flow of hydraulic operating water required for the operation of the classifying pool is introduced distributively in the bottom strata of the pool by means of an overhead pipe system extending into the pool; according to another embodiment, hydraulic operating water is derived by way of providing the auxiliary bottom plate in the form of a constriction plate allowing the pressure water from underneath to rise through the many holes in the constriction plate, even While sealing Water from the same pressure water source or chamber escapes around the edges of the constriction plate upwardly into the classifier pool.

One feature provides that at least one of the inter-engaging portions between the vibratory bottom and the stationary tank be rubber-coated in order that friction between the moving and the stationary parts be minimized by the lubricating effect of the water continuously supplied from below.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bounds of the claims, or of forms that are their functional as well as conjointly cooperative equivalents, are therefore intended to be embraced by those claims.

Figure l is a diagrammatic longitudinal sectional view of one embodiment of the apparatus, in which the auxiliary bottom plate is in the form of a constriction plate for supplying therethrough hydraulic operating water for the classifier pool.

Figure 2 is a cross sectional view taken on line 2-2 of Figure 1 employing the constriction plate.

Figure 3 is a cross sectional view taken `on line 3-3 of Figure l, to show another embodiment, namely that which employs a vibratable non-perforated bottom plate together with an overhead supply pipe system for introducing hydraulic operating water into the classifier pool.

Figure 4 is a greatly enlarged detail cross sectional view taken on line 4 4 of Figure 1, to show a grooved guide portion of the tank structure, with the vibratory bottom plate slidable in the groove.

Figure 5 is a longitudinal part-sectional side view of the apparatus, corresponding to the View of Figure l, although structurally more fully implemented.

Figure 6 is a plan view of the apparatus taken on line 6-6 of Figure 5.

Figure 7 is a greatly enlarged detail crosssectional view taken across the actuating mechanism on line 7-7 of Figure 5.

Figure 8 is a detail cross sectional view enlarged of the vibratory bottom and its grooved` guide portions, taken on line 8 8 of Figure 5.

Figure 9 is an enlarged detail vertical sectional view of a part of the actuating mechanism taken on line 99 of Figure 7.

Figure l0 is an enlarged detail vertical sectional view taken on line 10-10 of Figure 6 showing the sands discharge end portion of the classifier pool along with the structure directly associated therewith.

Referring to the diagrammatic views l, 2, 3 of the drawings the classifier apparatus comprises a stationary tank structure S containing a classifier pool P and a receiving chamber R operatively connected and communicating with the tank structure S as through a con* necting neck portion N, the chamber R to receive the coarse fraction oversize solids from the bottom strata of the classifier pool at the outlet end thereof.`

The tank structure S has an inlet end provided with a feedchute C receiving a supply of feed pulp thereto indicated by the arrow F. The opposite or discharge end of the tank structure has an overflow O1 for discharging the fines or undersize fraction from` the classifier pool into a discharge launder U. The tank structure S itself is defined by side walls W1 and W2, end walls E1 and 132, and a bottom B having a pressure Water supply connection Q. or vibratory false bottom in the form of a constriction plate Z is mounted within the tank structure S by means of horizontal guide grooves G1 and G2 formed in the sides of the tank structure. Thus, the solid bottom B and the constriction plate Z form between them a pressure water supply chamber Tf At the bottom of the discharge end of the tank structure S there is provided a discharge passage Oz for the oversize solids, this passage herein being termed the sands discharge passage. The neck or transitional portion N connects the tank structure S with the receiving chamber R, and Within this neck portion there is located a sands discharge Weir I operatively associated with the sands discharge passage O2 and rising to a level slightly higher than the height of the sands discharge passage 02. In this way, the oversize solids or sands migrating towards and through the passage O2 will spill at a controlled rate across the Weir l and into a pocket K formed `by the receiving chamber R. An adjustable overflow V provided in or associated with the receiving chamber R determinesa clear water level L2 as against the level Lr of the classifier pool, thereby determining the adjustable superelevation H of level L2 above level Ln and thus the rate at which oversize solids are allowed to spill across the submerged A reciprocatory CII discharge weir L An endless type of bucket elevator Y indicates the manner in which the oversize solids from the pocket K may be raised to a point of emergence for discharge over a chute indicated at D The horizontal reciprocatory or vibratory movement of the constriction plate Z is indicated by an arrow A. This plate is actuated to perform such reciprocatory movement by a Vibrator V1 disposed at the inlet end of the tank structure S and connected to the plate Z and through a diaphragm M provided upon the end wall E1 0f the tank.

The embodiment of Figure 2 illustrates a dual (mechanical and hydraulic) effect of the vibratory constriction plate Z which plate through its holes or perforations provides a multitude of rising jets or streams of hydraulic operating water for the classifier bath, while a quantity of water sealingly by-passes the constriction plate by way of the grooves G1 and G2 and around the edge portions of plate Z operating therein, such operating water for hydraulic classifying operation and edgewise sealing being supplied by and from the pressure water supply chamber Tf The vibrating device V1 is here diagrammatically indicated to comprise the vibrator unit V2 proper suspended from an anchoring point V3 and drivenby a motor V4, the unit V2 itself containing a pair of eccentrically loaded shafts V5 and Vs which when rotated in the manner indicated by arrows produce horizontally reciprocating forces adapted to impart vibratory movement to the plate Z, having a suitable frequency and a suitable length. of stroke.

ln the Figure 3 embodiment the reciprocatory bottom member is shown to be in the form of a solid plate P, while the operating water is supplied by means of a pair of stationary jet emitting horizontal pipes Il and J2 disposed near although suitably spaced `from the bottom plate. These jet emitting pipes have vertical supply connections I3 provided with control valve means J4, all as indicated in Figures 1 and 3.

The classifier apparatus in the embodiment of Figures 5 to 10 comprises substantially all the structural elements indicated in the diagrammatic Figure l although structurally more fully implemented.

Figure 5 represents the total tank structure 10 with an overall length La, this total length including the length L4 of a classifier tank 11 proper, the length L5 of a feed chute 12 at the inlet end of tank 11, the length Ls of a sands receiving chamber 13, and the.` length L7 of an interconnecting neck or transfer passage` 14 extending between the classifier tank 11 and the receiving chamber 13.

The classifier tank 11 comprises a body portion 1S hav ing a pair of side walls 16 and 17, an end wall 18 at the inlet end, an end wall 19 at the discharge end, and a dished or pan-shaped bottom portion 20 disconnectably fastened to the body portion of the tank. The feed chute 12 of end wall 18 supplies feed pulp to the feed end of the tank while end wall 19 provides at the top thereof an overflow edge 22 for discharging the fines fraction from the classifier pool into a discharge launder 23 itself unitary with the end wall 21.` At the bottom of the classifier pool at the discharge end is a sands discharge passage 24 for discharging the coarse solids fraction through the neck 14 and across a submerged sands discharge Weir 25 into a pocket 26 formed by the receiving chamber 13. The tank 11 is mounted upon a supporting structure 27 indicated by vertical legs or columns 28 and 28aL at one end and 29 and 29a at the other end, as well as by diagonal bracing indicated at 29b and 30. b

Within the tank is operatively mounted a horizontally reciprocable false bottom or bottom plate in the form `of a constriction plate 31 having holes or perforations 31EL uniformly disposed over the effective area of the plate. This constriction plate operates or reciprocates in horizontally grooved portions formed by the tank and so disposed that at least the lateral edge portions of the con 36 and 37 respectively, and that both anges are bolted together with a spacer strip 38 interposed between them in water tight fashion. The grooved portions or grooves 34 and 35 thus formed are here shown to be lined with a rubber coating 39, and a similar rubber coating 40 is also shown applied to the constriction plate 31. There is shown in each of the groove portions an operating clearance 41 indicating a loose operating fit of the plate in the grooves such that pressure water from the chamber 32. may force itself around the edge portions 31a and 31b of the plate and thus upwardly into the lateral longitudinal bottom corners 42 and 43 of the classifier pool at a rate whereby there is discouraged and prevented the entry of particles from the pool into the grooves.

Vibratory movement is imparted to the plate 31 by means of a vibratory device collectively designated by a numeral 44 and operatively connected to the plate 31 at the inlet end of the tank. This vibrating device 44 is here shown to comprise a vibrator unit 45 proper bodily and vrigidly connected to the adjacent end of the plate 31, although the weight of this vibrator unit is supported by a swingable element or link 46 suspended from an anchoring point 47. The vibrating unit 45 is driven by a motor 48 through a belt or other suitable endless trans mitting element 49 engaging a pulley 50 which is part of the vibrating unit 45 and drives one of two eccentrically loaded shafts mounted within that unit. These two shafts are geared up with one another in such a manner as to produce such free horizontally directed force as will impart to the constriction plate 31 reciprocatory or vibratory movement of desired and suitable characteristics.

The vibrating unit 45 is rigidly connected to the plate 31 and through a pair of diaphragms 51 and 52 respectively provided upon the end wall 18 of the classifier tank. That is to say, through each of these diaphragms extends a stem 53 and 54 respectively, which stems are parallel to one another, that is horizontally coextensive with the plate and with one another as well as rigidly connected to the end portion of the plate. Each of these diaphragmsv is cup-shaped and has a wide marginal or flange portion 55 (see Figure 9) fastened in sealing relationship to a flange 56 which is part of a neck portion 57 surrounding the respective stem, each neck 57 being shown as being welded to the end wall 18 of the tank. The flange portion 55 of the diaphragm is sealingly secured to the flange 56 as is indicated by a holding ring 58 and associated bolts 59. A narrow tubular portion 60 of the diaphragm hugs the stern 53 and is sealingly secured thereto as by a clamping element 61. Each of the stems 53 and 54 has an outer threaded end portion 62 extending through a bracket member 63 and secured thereto as by a pair of lock nuts 64 and 65, the bracket member 63 in turn constituting a part of the vibrator unit 45.

The neck or transfer portion 14 of the tank structure extending between the classier tank 11 and the sands receiving chamber 13 comprises in fact a flanged neck portion 66 extending from the classifier tank, and a flanged neck portion 67 extending from the receiving chamber 13, both neck portions being secured together by a flange connection indicated at 68. The receiving chamber 13 has a bottom support indicated by a footing 69, and is provided with an overflow pipe 70 providing an adjustable overflow level 71, the adjustability being indicated by a stack or sequence of removable rings 72.

Sands or coarse fraction solids collected in the pocket 26 of the receiving chamber are here shown as being coarse fraction discharge.

removed upwardly from that chamber to a point of emergence and discharge by means of an endless type bucket elevator 73 which may be of a type of construction suited for this purpose.

In the operation of the apparatus, vibratory movement of suitable frequency and suitable length of stroke is imparted to the false bottom plate while the jet emitting pipes provide an upward How from the bottom of hydraulic operating water in substantially uniform distribution over the bottom area.

The joint effect of the vibratory movement and of the upflow of hydraulic operating water at a controlled rate produce in the pool the desired classifying conditions whereby there are currently found in the pool a sands zone at the bottom containing substantially the oversize particles of the coarse fraction, a fines zone of undersize particles at the top to overflow, and an intermediate zone containing a mixture of undersize and oversize particles in teeter condition.

With all other operating factors assumed to be constant, the superelevation H controls the size separation inasmuch as it controls and maintains a corresponding density in the pulp column represented by the pool. Consequently, varying the superelevation as by means of a clear water overflow V adjustable in height, one may correspondingly vary and adjust the size separation or cut While there has been shown and described herein this manner of controlling the density of the classifier pool by way of establishing the superelevation (as defined by the overflow level in the sands receiving chamber), such control may be effected in other suitable ways, for example by way of measuring or obtaining indications of the density of the classifier pool, and employing them as criteria for adjusting and controlling the rate of discharge of coarse fraction material from the receiving chamber. Such manner of control requires eliminating the overflow means from the receiving chamber and it operates to throttle down the coarse fraction discharge means to a suitable extent when the density decreases to blow a desired value and to unthrottle the coarse fraction discharge means to a suitable extent when the density increases to above the desired value.

Automatic means may be provided for effecting such control by applying fluctuations or changes in the density of the pool through suitable relay action in a manner to control the rate of discharge of coarse fraction material from the receiving chamber maintaining the desired density in the pool. Such control is to function in the sense that an increase of density in the pool automatically effects a suitable increase in the rate of coarse fraction discharge, whereas a decrease of density automatically effects a suitable decrease in the rate of That is to say, density variations in the pool manifest themselves by the fluctuations of a hydraulic column communicating with the pool, which fluctuations are relayed through suitable instrumentation to actuate the coarse fraction discharge means through which the coarse fraction discharges from the receiving chamber thus to control the rate of coarse fraction discharge in a manner whereby the density in the pool is kept substantially constant at a desired value for which the automatic control device can be set to function.

The automatic control system just outlined to compensate for density fluctuations in the pool, may be employed to operate without necessarily requiring a submerged sands discharge weir associated with the bottom discharge passage of the pool, since the rate of transit of the material from the bottom zone of the pool through the passage may be controlled more directly by having the system control the rate of withdrawal of material accumulating in the receiving chamber or pocket; so the control system will function to compensate for density liuctuations in the pool by varying the accumulation or backlog of material in the receiving chamber. In this way, density fluctuations in the pool will currently be compensated for in a manner to automatically maintain a desired size separation.

A tentative example of the apparatus employing the Figure 3 embodiment of introducing hydraulic operating water by means of jet emitting pipes in the pool, provides a machine which may comprise a longitudinal classifying pool about 4 long, about 1 wide, and about 9 deep, with the sands discharge passage at the bot tom being about 1/z high and the sands discharge weir about 3A high, the pool area being 4 square feet.

As for the vibrating motion imparted to the bottom of the classifier pool, a practical or suitable operating range for the vibrating stroke under conditions in this example may be considered to lie in a range of about li to about M1", with the stroke frequency covering a practical range of 600 to 1000 reciprocations per minute, and a stroke length about lye" at a stroke frequency on the order of 700 reciprocations per minute. The jet emitting pipes which supply the hydraulic operating water here comprise longitudinally extending horizontal pipes having a clearance from the bottom of the pool of about 1/z, with center to center spacing between the pipes of about 6", and the center of each pipe in turn spaced a distance of about 3 from the respective side walls of the pool. A pair of jet-emitting pipes provided parallel to one another may each be 4 long of 1/z standard pipe, hav-ing .622 inside diameter and .840 outside diameter, with a spacing between the jet holes of 1%6" center to center, the jet holes themselves to be drill holes produced with No. 37 drill, and having an area each of .00849 square inch, the nominal diameter of the drill hole being .1040 inch, and the total open area of the holes being 1.22 square inches for a total number of 144 holes. Water is to be emitted from the pipes by jets provided by a double row of jet orilices in each pipe s'o disposed that a row of jet openings at each side of each pipe would emit jets at an angle of about 20 below the horizontal. Head loss is placed at 1 foot water column for a flow rate of 18 gallons 0f operating water per minute. The jet emitting pipes extend in the direction of vibration or reciprocation imparted to the bottom of the pool.

With a feed to the classiiier pool consisting of a deslimed sands mixture having a range of sizes of -20 to 200 Tyler mesh and feeding 79.5 tons per day (dry weight) it is considered that about 59.0 tons per day (dry weight) pass through the underflow, and about 20.5 tons per day (dry weight) pass through the overtiow, the separation in terms of the size of the cut to be at 250 microns with a superelevation being maintained at 31A" and a supply of hydraulic operating water at the rate of 18 gallons per minute.

I claim:

1. Apparatus for the hydraulic classification treatment of pulp containing a mixture of particle sizes ranging from line to coarse, to eiect the separation of the mixture into a fraction of fines and a fraction of coarse size material, defined as undersize and as oversize particles respectively, which apparatus comprises a classifying pool hav ing said mixture supplied Lthereto in one portion thereof and said fractions discharged from other portions, said pool proper being confined within a tank structure having side and end walls as well as a solid bottom, an auxiliary bottom plate member mounted in spaced relationship with respect to the solid bottom to perform horizontal reciprocatory sliding movement within said tank structure', which tank structure is formed with horizontally extending grooved guide portions for the marginal portions of said auxiliary plate member to operatively and slidably engage therein while providing a pressure water chamber between said plate and the surrounding solid bottom portion, actuating means operatively connected with said auxiliary bottom for imparting thereto horizontal reciprocatory movement, controllable pressure water supply means for said chamber whereby pressure water is forced to sealingly pass into said grooved portions and to escape therefrom around the marginal portions of said plate member into the classifier pool above, controllable water supply means for distributively introducing hydraulic op erating water into the bottom strata of the classifier pool whereby the water rises in substantially uniform distribu- 'tion from the bottom, and whereby there are formed and maintained in said pool horizontal classification zones comprising substantially a sands zone of coarse fraction particles at the bottom, a fines zone of undersize particles at the top, and an intermediate zone containing a mixture of undersize and oversize particles in teeter condition,- so that by the concurrent action of the horizontal motion of the bottom face and of the rising flow of the operating Water being adapted to produce overflow and underflow size fractions each substantially free from stray particle Sizes of the other, there being provided an overiiow weir for overow discharge of undersize particles from said top zone of the pool, an underflow discharge passage at the bottom, adjustable means for controlling the rate of underflow discharge through said passage.

2. Apparatus according to claim 1, in which the actuating means for the auxiliary bottom member comprise a vibrating unit disposed outside the tank and adapted to impart horizontal vibratory motion to said bottom, a motion transmitting member operatively connecting the vibrating unit through the tank wall with said bottom and diaphragm means sealingly interconnecting said motion transmitting member with said wall.

3. Apparatus according to claim 1, in which the bottom plate member is in the nature of a solid plate, and the water supply means comprise jet emitting conduit means disposed adjacent to and spaced from said bottom plate, provided with controllable means for supplying water from above to said jet emitting means.

4. Apparatus according to claim l, characterized thereby that said bottom plate member is provided with perforations to constitute a constriction plate for admission therethrough of operating water from said pressure water chamber upwardly into said classitier pool.

5. Apparatus according to claim 1, in which said underflow discharge passage comprises a submerged Weir .spaced outwardly from and higher than said passage, across which weir coarse size material is adapted to discharge, with the addition of a receiving pocket for receiving the discharging coarse material, said receiving pocket having discharge means for the coarse material as well as adjustable clear water discharge means for maintaining a clear water level in said pocket at a desired elevation.

References Cited in the tile of this patent UNITED STATES PATENTS 1,544,999 Lequeux July 7, 1925 2,302,588 Weber Nov. 17, 1942 FOREIGN PATENTS 594,211 Germany Mar. 14, 1934 

1. APPRATUS FOR THE HYDRAULIC CLASSIFICATION TREATMENT OF PULP CONTAINING A MIXTURE OF PARTICLE SIZES RANGING FROM FINE TO COARSE, TO EFFECT THE SEPARATION OF THE MIXTURE INTO A FRACTION OF FINES AND A FRACTION OF COARSE SIZE MATERIAL, DEFINED AS UNDERSIZE AND AS OVERSIZE PARTICLES RESPECTIVELY, WHICH APPARATUS COMPRISES A CLASSIFYING POOL HAVING SAID MIXTURE SUPPLIED THERETO IN ONE PORTION THEREOF AND SAID FRACTONS DISCHARGED FROM OTHER PORTIONS, SAID POOL PROPER BEING CONFINED WITHIN A TANK STRUCTURE HAVING SIDE AND END WALLS AS WELL AS A SOLID BOTTOM, AN AUXILIARY BOTTOM PLATE MEMBER MOUNTED IN SPACED RELATIONSHIP WITH RESPECT TO THE SOLID BOTTOM TO PERFORM HORIZONTAL RECIPROCATORY SLIDING MOVEMENT WITHIN SAID TANK STRUCTURE, WHICH TANK STRUCTURE IS FORMED WITH HORIZONTALLY EXTENDING GROOVED GUIDE PORTIONS FOR THE MARGINAL PORTIONS OF SAID AUXILIARY PLATE MEMBER TO OPERATIVELY AND SLIDABLY ENGAGE THEREIN WHILE PROVIDING A PRESSURE WATER CHAMBER BETWEEN SAID PLATE AND THE SURROUNDING SOLID BOTTOM PORTION, ACTUATING MEANS OPERATIVELY CONNECTED WITH SAID AUXILIARY BOTTOM FOR IMPARTING THERETO HORIZONTAL RECIPROCATORY MOVEMENT, CONTROLLABLE PRESSURE WATER SUPPLY MEANS FOR SAID CHAMBR WHEREBY PRESSURE WATER IS FORCED TO SEALINGLY PASS INTO SAID GROOVED PORTIONS AND TO ESCAPE 